Oh dear, we have a predicament. I don't actually think any of these guys is scum. Sorry if some think this isn't the best strategy, but I use the 'why would they do this if they were scum?' approach. I try to think like a mafia and how they would play this game best.
Ifrit - Why would he create a gimmick where he must post in rhyme knowing he'd have to keep it up all game? If he's smart enough to do this, he's smart enough to know the oddest person on day 1 usually gets the votes.
Bahamut - Why would he be taking such an active role against Ifrit if he was mafia? Ifrit's weird behavior would speak for itself. I think he is the most likely of the three though because going after Ifrit seems too obvious.
Cactuar - I don't think a mafia would roleclaim on day 1 if they could help it, and he didn't have much on him when he made it. Don't know if I believe the claim because we haven't even had a night phase yet.
This is why I voted Shiva, someone who is pretty much laying low, and I don't think some of her posts make that much sense. But it is too late to convince you guys otherwise.
I am tempted to end this with a vote for Bahamut, because if he is mafia that would clear up Shiva and Leviathan, two people I am iffy on.